Formation of thick titanium carbide films by the hollow cathode discharge reactive deposition process

Thick titanium carbide films were successfully deposited on mild steel sheets using a hollow cathode discharge reactive deposition process. Methane, ethylene and acetylene were used as reactant gases during the titanium evaporation and the substrates were either negatively biased or grounded. The deposited films were characterized by microhardness measurements, X-ray diffraction, Auger electron spectroscopy and secondary ion mass spectrometry. The results are discussed with regard to deposition conditions and chemical composition.     

Crystallography of epitaxially grown molybdenum on sapphire

Molybdenum thin films were deposited onto (0001), ($\text{1012}$) and (10$\text{12}$) sapphire substrates by electron-beam evaporation in ultrahigh vacuum. The surface morphology and crystallographic orientation of these films were characterized by electron microscope replication and reflection electron diffraction. The effect of the crystallographic plane of the sapphire substrates as well as that of the deposition rate on the crystallographic orientation of the deposited molybdenum films were examined in the temperature range 25°-1000°C. The epitaxial temperature range was 600°-900°C for basal plane substrates and 300°-1000°C for ($\text{1}$012) and (10$\text{1}$2) substrates. The orientation of the deposited film was strongly dependent on that of the sapphire substrate.     

Related structural,electrical and photoelectrical properties of vacuum-deposited GaP thin films

GaP thin films with thicknesses from 0.1 to 0.6 μm were prepared by the thermal evaporation of the compound GaP onto quartz substrates at temperatures from ambient temperature to 740 °C. The properties of the films depended strongly on substrate temperature and deposition rate. With increasing substrate temperature the film structure changed from amorphous to textured polycrystalline with a strong [100] texture. The temperature of the amorphous-to-crystalline transition depended on deposition rate and was found to be 360 and 400 °C for deposition rates of 2 and 10 Å s^-1 respectively. At these temperatures the electrical resistivity of the films fell sharply from 10⁸ Ω cm to a minimum value of $\text{5 × 10}{}^4\text{Ω}\text{cm}$, after which it increased again with increasing temperature. The amorphous films exhibited a moderate photosensitivity with a maximum value near the temperature of the structural transition; above this temperature the films lost their photosensitivity completely. The spectral dependence of the photoconductivity was measured and an attempt was made to interpret the observed spectra.     

The structure of nickel and cobalt films on the (111) surface of n-type silicon

Films of Ni and Co have been grown on the (111) surface of phosphorus doped n-type silicon by evaporation in high vacuum. For both systems polycrystalline films resulted for all substrate temperatures except in the range 250° to approximately 400°C when f.c.c. Ni or Co grew with the orientation Ni/Co (110)6Si (111); Ni/Co [$\text{1}$10]6Si [$\text{2}$11].     

Reactive ion plating of metal oxides onto insulating substrates

SnO₂ and In₂O₃ films were produced by evaporation and by magnetron sputtering of the elements in an atmosphere containing oxygen. The insulating substrate of glass or plastic was water cooled and made one electrode of an r.f. discharge in the gas. The optical and electrical properties of the films indicated that the energy of the bombarding ions, measured by the d.c. standing voltage that developed on the substrate due to r.f. discharge, gave properties that had only previously been obtained using substrate temperatures of 450°C and above.The SnO₂ films were insulating. The In₂O₃ films were conducting, a minimum value of the sheet resistivity ($\text{187 Ω}\text{□}$ being achieved with evaporated films at a bias of ?400 V and a value of $\text{630 Ω}\text{□}$ being obtained with sputtered films at a bias of ?160 V with a 30 vol.% O₂?70 vol.% Ar gas mixture. All films were about 80 nm thick. The ultraviolet absorption edge position proved to be related to the refractive index and the conductivity. Hall effect measurements gave a carrier concentration of 4 × 10²⁵ m^?3 with a mobility of 1.9 × 10^?3 m² V^?1 s^?1 for the best sputtered film.     

Physicochemical and structural characteristics of TiC and VC thin films deposited by DC reactive magnetron sputtering

Vanadium carbide and titanium carbide films were deposited on Si substrates by direct current reactive magnetron sputtering, varying the substrate temperature during deposition and the reactive gas (CH₄) pressure. The physicochemical and structural properties of the films were characterized for stoichiometric films (V/C = 1 and Ti/C = 1), which display good performance concerning wear, friction, and corrosion. The techniques used to characterize the films were Rutherford backscattering spectrometry in channeling geometry, ¹²C(α,α)¹²C nuclear resonant scattering, glancing angle X-ray diffraction, X-ray reflectometry, and X-ray photoelectron spectroscopy. The results revealed that the ideal conditions for deposition of these films are a CH₄ partial pressure of 0.5 × 10⁻³ mbar and a substrate temperature of 400 °C. In such conditions, the deposition rates are 7 nm s⁻¹ for TiC and 8.5 nm s⁻¹ for VC at a target power density of 5.5 W cm⁻². The density of the films, as determined here by X-ray reflectometry, are slightly higher than those for the bulk materials.     

Reactive ion plating (RIP) with auxiliary discharge and the influence of the deposition conditions on the formation and properties of TiN films

In this paper we attempt to analyse the processes of reactive evaporation, activated reactive evaporation and reactive ion plating on the basis of earlier theoretical studies. Our initial results concerning the dependence of phase formation on the deposition rate and working gas pressure in reactive evaporation and ion plating indicate that the proposed ideas can in principle be applied and this was also shown analytically by the dependence of the microhardness of TiN films on the pressure. At low partial pressure of nitrogen TiN_x films with a stoichiometric coefficient x near unity are not formed. These near-stoichiometric films are of low hardness. The decrease of microhardness with increasing nitrogen pressure (p 624 × 10^-2 Pa) can be explained by physical effects, such as the inclusion and scattering of gas. Initial studies on the wear properties of such films have indicated their potential in technological applications.     

Ion beam reactively sputtered silicon nitride coatings

An ion beam source was used to deposit silicon nitride films by reactive sputtering a silicon target with an Ar+N₂ beam. The nitrogen fraction in the sputtering gas was 0.05 to 0.80 at a total pressure of 6 to 20×10^?5 torr. The ion beam current was 50 mA at 500 V. A rate of deposition of about 2 nm min^?1 (0.12 μm h^?1) was found, and the spectra indicated that Si₃N₄ was obtained for a fraction of nitrogen higher than 0.50. However, the AES spectra also indicated that the sputtered silicon nitride films were contaminated with oxygen and carbon and contained significant amounts of iron, nickel, and chromium, most probably sputtered from the holder of the substrate and target.     

X-ray diffraction studies of Bi2O3 films prepared by reactive and activated reactive evaporation

Bi₂O₃ films were prepared by reactive evaporation and by activated reactive evaporation. The various phases obtained were studied using X-ray diffraction. Reactive evaporation always produced β-Bi₂O₃ films. For a given substrate temperature, low rates of deposition (less than 20 Å s^-1) always produced β-Bi₂O₃ films, whereas high rates of deposition (greater than 35 Å s^-1) produced α-Bi₂O₃ films when the oxygen partial pressure inside the chamber was kept constant. Films prepared by both reactive evaporation and activated reactive evaporation at substrate temperatures below 400 K were amorphous in nature and at higher substrate temperatures polycrystalline films were produced. The results obtained on annealing these films in high vacuum and in air are also reported.     

Preparation of hexagonal potassium tungsten bronze thin films by thermal vacuum evaporation

$\text{K}{}_{\mathrm{x}}\text{WO}{}_{\mathrm{<mtext>3+</mtext><mtext>x</mtext><mtext>2</mtext>}}\text{(}\text{x}\text{= 0.3)}$ thin films have been prepared by the thermal vacuum evaporation technique. Depending on the substrate temperature during deposition, either amorphous or crystalline films could be obtained. X-ray diffraction patterns and pole-figure information revealed that fresh crystalline films deposited on a hot (about 400°C) substrate of indium-tin oxide on glass microscope slides had a preferred orientation, with the c-axis perpendicular to the surface of the film. SIMS depth profiles and RBS experiments were used to confirm the stoichiometry and uniformity of the chemical components in the thermally deposited films.     

Properties of indium oxide films prepared by the reactive evaporation of indium

Indium oxide films with an electrical resistivity of about $\text{4 × 10}{}^{\mathrm{?4}}\text{Ω}\text{cm}$ and good optical quality were prepared by the reactive evaporation of pure indium in the presence of 10^?4 Torr of oxygen. The Auger electron spectrum of these films shows a deficiency of oxygen and corresponds to a composition which can be represented as In₂O_2.85. In the absence of foreign doping agents, the conduction electrons are provided by indium atoms which are adjacent to oxygen vacancies and act as a donor level. The electrical conductivity of the films is shown to be modulated by variations in the partial pressure of oxygen over the film which change the extent of the non-stoichiometry of the oxide by incorporation of oxygen into or extraction of oxygen from the film.     

Characterization of antimony-doped tin oxide films for solar cell applications

Transparent conducting undoped tin oxide (SnO₂) and antimony-doped tin oxide (ATO) films were deposited onto Pyrex glass and single-crystal silicon substrates using an inexpensive chemical vapour deposition system. SnCl₂ and SbCl₃ were used as the source reagents with oxygen and nitrogen respectively as the carrier gases. The deposition conditions were as follows: temperature, 350–500 °C; oxygen flow rate, 0.8–3.25 1 min^-1; nitrogen flow rate, 0–0.1 1 min^-1; deposition time, 5–20 min. The antimony concentration in the film and its physical properties were the same on both substrates. A figure of merit (Tr¹⁰/R_sh where Tr is the transmission at a particular wavelength and R_sh is the sheet resistance) was used to compare the performance of these films. The maximum figure of merit for SnO₂ films $\text{(1.43 × 10}{}^{-3}\text{Ω}{}^{-1}\text{(}\text{Tr}\text{= 95\% and R}{}_{\mathrm{<mtext>sh</mtext>}}\text{= 420 Ω/□))}$ was obtained when they were deposited at 500 °C with oxygen at a flow rate of 1 1 min^-1. The sheet resistance of antimony-doped films is a minimum at 3 mol.% Sb and the transmission decreases as the antimony concentration increases. The maximum figure of merit obtained for ATO films was $\text{6.78 × 10}{}^{-3}\text{Ω}{}^{-1}\text{(}\text{Tr}\text{= 90.6\% and R}{}_{\mathrm{<mtext>sh</mtext>}}\text{= 55 Ω/□)}$ for an antimony content of 3 mol.% and a nitrogen flow rate of 0.07 1 min^-1. These results are explained theoretically and are compared with those reported by other workers.     

Improved wear and corrosion resistance of chromium(III) plating by oxynitrocarburising and steam oxidation

Postsurface treatments, such as oxynitrocarburising and steam oxidation, were applied to amorphous Cr plating on SM45C mild carbon steel obtained from a trivalent (III) chromium bath to improve wear and corrosion properties. Higher wear properties of hardness (HV 1450), wear rate (1.9×10⁻⁶ mm³/rev) and friction coefficient (0.4) were found for both the oxynitrocarburised and the steam-oxidized Cr platings due to the formation of chromium carbide, Cr₇C₃, during the treatments. Excellent corrosion resistance was also observed for the posttreated Cr platings due to the crack healing effect as a result of the formation of iron oxides (Fe₃O₄, Fe₂O₃) and/or nitride (Fe₄N), suggesting that these treatments are highly effective in enhancing wear and corrosion resistance of the chromium platings.     

Some electrical properties of thin Yb2O3 films produced by different technological methods

Results obtained from investigations of the electrical conductivity and the permittivity of Yb₂O₃ films in MIM structures are presented. Thin films of Yb₂O₃ were produced by four different methods: the evaporation of Yb₂O₃ by an electron beam, the evaporation of Yb₂O₃ from tungsten heaters, the reactive evaporation of ytterbium in oxygen and the evaporation of thin ytterbium films followed by their oxidation in air. The structure of both amorphous and polycrystalline Yb₂O₃ films and their electrical properties were found to depend on the conditions under which the films were obtained $\text{(ε = 7?50; ? ≈ 10}{}^9\text{?10}{}^{12}\text{Ω}\text{m}\text{)}$.     

Structural and electrical properties of Ta and Ta nitrides deposited by chemical vapour deposition

It has been shown that single-phase α-Ta, β-Ta, Ta₂N, TaN(f.c.c.) and Ta₃N₅ films can be produced by chemical vapour deposition (CVD). The structure of the microcrystalline deposits has been investigated by transmission electron microscopy.Electrical measurements reveal that the resistivities of CVD films are comparable with those of sputtered films. However, the temperature coefficient of resistivity (TCR) of β-Ta, Ta₂N and TaN(f.c.c.) is positive, varying between 30 and $\text{300}\text{ppm}\text{K}$. In the case of Ta₃N₅ the TCR is negative $\text{(}\text{α～?40 000ppm}\text{K}\text{)}$ and the resistivity has a value of about 6 μ cm.     

Elimination of the 16O2+ effect in backscattering studies of thin film reactions

Thin films of the ternary thiogallate compounds CdGa₂Se₄ and CdGa₂S₄ were prepared by the vacuum evaporation and the flash evaporation methods. The optical absorption spectra were studied in the visible range of radiation. Analysis of the absorption curve indicated close agreement with that of the bulk material. Plots of α²versus$\text{h}\text{?}$ω yielded 2.51 eV and 3.50 eV as the values of the energy gaps for direct transitions for thin films of CdGa₂Se₄ and CdGa₂S₄ respectively. Plots of $\text{(α}\text{h}\text{?}\text{ω)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$versus$\text{h}\text{?}$ω before and near the fundamental absorption edge did not give convincing support for indirect transitions in these compounds.     

Structural and mechanical properties of multi-element (AlCrMoTaTiZr)Nx coatings by reactive magnetron sputtering

(AlCrMoTaTiZr)N_x high-entropy films were deposited on silicon wafer and cemented carbide substrates from a single alloy target by reactive RF magnetron sputtering under a mixed atmosphere of Ar and N₂. The effect of nitrogen flow ratio R_N on chemical composition, morphology, microstructure, and mechanical properties of the (AlCrMoTaTiZr)N_x films was investigated. Nitrogen-free alloy film had an amorphous structure, while nitride films with at least 37 at.% N exhibited a simple NaCl-type FCC (face-centered cubic) structure. Mixed structures occurred in films with lower nitrogen contents. Films with the FCC structure were thermally stable without phase decomposition at 1000 °C after 10 h. The (AlCrMoTaTiZr)N film deposited at R_N = 40% exhibited the highest hardness of 40.2 GPa which attains the superhard grade. The main strengthening mechanisms for this film were grain-size and solid-solution strengthening. A residual compressive stress of 1.04 GPa was small to account for the observed hardness. The nitride film was wear resistant, with a wear rate of 2.8 × 10^− 6 mm³/N m against a loaded 100Cr6 steel ball in the sliding wear test. These high-entropy films have potential in hard coating applications.     

Study on adhesion and wear resistance of multi-element (AlCrTaTiZr)N coatings

Multi-element (AlCrTaTiZr)N films were deposited on cemented carbide and M2 steel substrates by reactive RF magnetron sputtering. Prior to nitride film deposition, an interlayer between the film and the substrate was introduced to improve adhesion property. The influence of interlayer materials (Ti, Cr, and AlCrTaTiZr alloy) and interlayer thickness (0–400 nm) on the adhesion and tribological properties of films was investigated. In this study, the nitride film deposited at R_N = 20% exhibited the highest hardness (35.2 GPa) and the lowest residual compressive stress (? 1.52 GPa), and was prepared as the top layer for further testing. The interlayer materials can effectively improved the film adhesion onto the cemented carbide substrates, and the adhesive failure was not observed even under the normal load of 100 N. For M2 steel substrates, only the Cr interlayer can slightly improve the film adhesion, and the cohesive and adhesive failure can be found at relatively lower applied load. The optimal interlayer thickness was 100–200 nm for the 1 µm-thick (AlCrTaTiZr)N film and can be related to the stress evolution. The friction coefficient and wear rate for the (AlCrTaTiZr)N film were 0.82 and 4.9 × 10^? 6 mm³/Nm, respectively, and almost kept constant under different interlayer materials and thickness. The worn-through event of the nitride film during tribological test occurred easily owing to its poor adhesion behavior, and can be improved by interlayer additions.     

The fracture toughness of cemented tungsten carbides

The fracture toughness of a number of cemented carbide alloys have been determined; using a wedge-impact method for precracking. The materials were of WC-Co type with cobalt content ranging from 6 to 25 wt-% and mean carbide grain size between 1.0 and 3.3 μ m. Within the investigated composition range the fracture toughness decreases almost linearly with increasing hardness of the materials from 20.3 MN/n^{$\text{3}\text{2}$} at 800 HV (25 wt-% Co) to 9.8 MN/m^{$\text{3}\text{2}$} at 1700 HV (6 wt-% Co). The standard deviations determined from more than 20 tests were 0.7 and 0.3 MN/m^{$\text{3}\text{2}$} respectively.The fracture toughness increases with increasing carbide grain size.     

Oxygen incorporation in hexagonal and amorphous nickel films

The incorporation of oxygen in r.f. sputtered nickel films 200–400 Å thick was observed by means of intensity analysis of electron spectroscopy for chemical analysis spectra from the Ni 2p_{$\text{3}\text{2}$} and O 1s energy levels. The films were of f.c.c, h.c.p. or amorphous structure depending on the deposition rate and temperature and also the vacuum annealing conditions. The structures were determined by electron diffraction. The surface regions of the metastable films of h.c.p. and amorphous structures contain excess oxygen which is incorporated at positions other than the octahedral coordination sites.